e-pilot was using a very, very old version of the 737-300! That's why I never experienced the problems mentioned here.The problems mentioned usually appear when approaching much too fast. So keep to the Vref speeds given in the help-menu of the 737-300 available here or via FGData.

I hope still for a correct 737-classic. With realistic MCP-Panel (not the one from the 777!!) , PFD, steam gauges and realistic working Autoflight System. All informations needed are available on the web!

Soitanen, you are right, I'm sorry!Mr. Culp said that the bug should be in the ground effect lift table, so I looked there.

Nethertheless, I tried the corrected fdm, and from my subjective point of view I don't see much difference than before. (What is good, as it behaves like described by many pilots; flightmanuals etc...)

It does not surprise me much: h_b-mac-ft is actually the ratio of height of AeroRP over the wingspan - the bug appears only between 0 and 0.1 "h_b-mac-ft"- means at 0 "h_b-mac-ft" it got factor 10 less drag (kCDge), at more than 0.1 it got factor 1.On normal ground run I only see a difference of factor approx. 4 of kCDge. (now 0.48 kCDeg vs former 0.18 kCDge)

The bug started at 0.1 "h_b-mac-ft" which is is about 15ft AGL- a height where you usually begin to put the thrust levers back to idle.

So the effect of this bug does not completly explain why you got trouble landing the 733. Even with the bug I never could reproduce you experience

My bug was, that on full flaps and idle thrust I can fly along runway with very little deceleration. Speed didn't drop, and I can fly half of runway. Now speed drops normally and landing seems to be realistic.

Thank you very much for finding that bug Soitanen and Pierre - I have corrected the drag due to ground effect table. I have over 1000 landings in the 733 with the bug in place and have not experienced what you describe, but I have fixed it anyway as it is an obvious bug in the code. Pierre, my 733 does not have a 777 MCP - it is an exact replica of a 737-300 MCP and so is the PFD. If you have that in yours it is not the one I have been working on.

Hello guys,I have to tell sorry to you and particularly to Soitanen that I incorrectly claimed the neutral position of the control column stays same regardless to the trim settings. I is not true. Mach trim actuaator is connected through a mechanical linkage to the stabilizer, so every particular stabilizer position has its own neutral position of the elevator and controll column. It is described explicitly in the document 27-31-00 on this adress:

I have found interesting graph, which shows wind speed, on which parked plane will make nose-up, due to stabilizer position and CG position (5% and 30% MAC located).Weight was written, so I calculated actual moments from weight, lift and drag forces and calculated force, that stabilizer generate. After that I recalculate this force into moment and change it due to different gear and CG position, and have graph, showing efficiency of stab due to it's position.May be I miss something and my whole calculations are wrong? I tried to fly with it, making my mixture control knob on joystick as stabilizer control. It's too sharp, becasu of too small resolution of the knob. Where I can find actual stabilizer change speed?

to e-pilot: may be you can make repository on github with this 737-300, it will be easier to contribute to it. I see some errors and I want to improve aircraft.

Normal electric trimming of the stabilizer is done at one of two rates as controlled by flap position. Trimrate with flaps retracted is 1/3 the trim rate with flaps extended. The autopilot actuator also trims atone of two rates as controlled by flap position. High speed autopilot rate is equal to the normal electriclow speed rate. The low speed autopilot rate is 1/2 the rate of the high speed autopilot rate.

(19)Do a test of the high (flaps down) stabilizer trim rate: (a) Move the stab trim switches on the control wheel to the NOSE UP (stabilizer leading edge down) position and hold until the stabilizer stops. (b) Do the following to measure the time it takes for the stabilizer to move from the leading edge down position to the leading edge up position: 1 Move the stab trim switches on the control wheel to the NOSE DOWN position and hold until the stabilizer stops. 2 Make sure that the time from the start to stop of stabilizer movement is between 17 and 24 seconds.

(22)Do a test of the low (flaps up) stabilizer trim rate: (a) Move the stab trim switches on the control wheel to the NOSE DN (stabilizer leading edge up) position and hold until the stabilizer stops. (b) Do the following to measure the time it takes for the stabilizer to move from the leading edge up position to the leading edge down position: 1 Move the stab trim switches on the control wheel to the NOSE UP position and hold until the stabilizer stops. 2 Make sure that the time from the start to stop of stabilizer movement is between 43 and 57 seconds.

From these information you can easily calculate stabilizer rates (speeds) in units of trim per second.

There is version from e-pilot's link (this morning) and 2 small additions (now, will grow).

1. ASI now correctly operates with Vmo needle. It were absolutely wrong. Now it really calculates 0.82M at aircraft location, makes choise between 340 kts or 0.82M (which is smaller) and point it.2. VSI now shows direct vertical speed, not barometrical. Real aircraft use IRS for this purposes.3. ALT pressure knob can be controlled via mouse wheel normally, not too big changes in pressure.

My friend is captain of 737 in Transaero, but he have not Flightgear installed. Soon I have planned meet with he and Flightgear, hope he will help to provide some interesting information.

About stabilizer - it's not in repo now, still experimenting, but seems to be plausible.Also, I tried to compute Cl max via this formula: Clmax=2*weight/(rho*speed^2*wing_area). I used stall speed for different weights in 737 FCTM. And I found some interesting numbers. Cl max for clean wing is 1.48 (in current FDM we have it only 1.20). But more interesting is flaps infuence: at only 5 degrees Clmax is 2.18! Little table:

Also at this page http://www.b737.org.uk/techspecsdetailed.htm we can find CLmax (Land @ MLW) - 2.88. So my calculations seems plausible, and I have plans to redo FDM (Lift-Drag values, diferent stab and elevator control).

I have pushed into github first FDM change. Now trimming acts on stabilizer, not on elevator. Outside animation works properly.What is realized: different speeds of trimming due to flaps position and autopilot engagement, different ranges of stabilizer movement due to flaps position, realistic (as I have calculated earlier) aerodynamic influence of stabilizer.What needs to be done: possibility to manual trimming (via mousewheel when pointing on trimwheel), add switch STAB OVERRIDE (now stab can be trimmed in any way not regarding to control column position), add stab position indicator near trim wheel. Unfortunately I have lack of 3D modelling skills. e-pilot, come on, give me your nickname on github, I'll give you push right to work together!

I search for info: what gear ratio have trim wheel to stab? How many turns need to be done to move stab for 1 unit, for example? I have overlooked this document (big thanks Honzaku for the link) 27-41: HORIZONTAL STABILIZER TRIM CONTROL SYSTEM, but I cant find the value...

Well that is for 737-700 but since this manual trim in Boeings is fossil from the times of the good old 707 and nobody uses it anyway I am pretty sure Boeing engineers left it unchanged within the whole 737 family.

This source refers to some pilot report and gives slightly different number 256 revolves (for 737NG):

Honzaku wrote in Tue Jan 21, 2014 1:45 pm:Anyway, it could be a question for your friend captain. But I doubt he's ever measured it.

Hello! I'm sure, that he never try to count number of revolutions to trim the stab But I'll ask!

2 updates in github repo: - new tiller steering menu: now nosewheel can turn from pedals only for 7 degrees (like real one), ground steering must be using tiller. Just open menu, grab knob and rotate it. Number in degrees is current position of nosewheel (you can turn pedals and see changes). - new spoilers logic: fixed animation of ground and flight spoilers (they were confused). Now keys "j" and "k" controls Speedbrake lever (animation is note done yet). It have 7 positions (can be controlled via property tree, see b733/controls/flight/spoilers-lever-pos, soon position will be seen on screen like flaps). Positions:0 - down1 - armed2 - 25% of flight detent flight spoilers3 - 50% of flight detent flight spoilers4 - 75% of flight detent flight spoilers5 - Flight detent6 - Spoilers up (flight and ground)If you set spoilers to armed and land, flight and ground spoilers will automatically deploy.

And some new updates again:- another engine max thrust - 20000 lbs. It's base engine for 737-300. 23500 was never installed on -300 (as I found info in internet);- some aerodynamic coefficients taken from documents, in which aero data are compared between real (taken from data set for 737-300 simulator) and generated by DATCOM. After some test flights I see no flight bugs and decided to push it in repo.

Some wind tunnel test results for 737-100 (regrettably, the data are not relevant for 733 due to different wing), for some reason these NASA report links don't work in Firefox, you have to use Internet Explorer: